Perishable products, such as packaged foods, have a shelf life which must be ascertained so that stale product is not sold to consumers. The shelf life of such products is commonly imprinted upon the package as the “expiration date” or “freshness date”. Manufacturers, distributors and retailers of perishable products commonly prioritize the shipment, distribution and display of such products based upon the expiration date or freshness date of the product to reduce the amount of expired product which must be discarded.
One example of efforts taken to increase the shelf life of perishable products is flushing of the packaging with an inert gas, such as nitrogen, to reduce the oxygen concentration within the packaging.
The shelf life of a perishable product can be determined by several methods depending upon the particular product involved (i.e., potato chips v. soft drinks). One of the variables often involved in determining shelf life is the volume of the container. Such a calculation is relatively simple when the container is a rigid container with a fixed volume (i.e., a paperboard cylinder such as that employed to package PRINGLES® potato crisps), but becomes much more difficult when the container has a variable volume (i.e., a MYLAR potato chip bag).
Currently available instruments for measuring or estimating the volume of a variable volume container, such as those disclosed in U.S. Pat. Nos. 4,268,967 and 6,189,223, are unacceptably inaccurate, prohibitively expensive, difficult to conduct and/or slow.
Accordingly, a need exists for an inexpensive, quick, easy and accurate method and instrument for measuring the volume of a variable volume container.